The present invention relates to a thermosetting polyether resin and a polyether resin having low dielectric constant.
More particularly, the present invention relates to a thermosetting polyether resin used for insulation and coating in various electronic devices, a polyether resin having low dielectric constant used for insulation and coating of hypervelocity computing devices (MPU), a process for producing the same, and a coating solution for forming an insulation film containing said resin.
Further particularly, the present invention relates to a thermosetting polyether resin having low dielectric constant property, high heat resistance, chemical resistance and high film strength, a process for producing the same, and a coating solution for forming an insulation film containing said thermosetting polyether resin.
High speed performance of LSI is attained by reduction in size of transistors constituting the LSI. Recently, the wiring distance has decreased by this reduction in size, and the signal propagation delay (wiring delay) and the crosstalk noise between adjacent wirings have become remarkable, providing important problems preventing the high performance of LSI itself. For solving these problems, lowering of the relative dielectric constant of an insulation film burying spaces between wirings is in investigation. Though a SOG (Spin on Glass) film conventionally used as an insulation film is an effective material since an insulation film can be formed easily on a device substrate by coating and baking, the dielectric constant thereof is from 3.0 to 3.9, being not sufficiently lower. When the distance between wirings is 0.25 xcexcm or lower, an insulation film having a relative dielectric constant preferably less than 3.0 is required.
Use of a polyether resin for forming an insulation film is known. For example, Japanese Patent Application Laid-Open (JP-A) No. 9-246429 discloses an example using, as an insulation material, a polyphenylene ether resin obtained by oxidation polymerization. However, a polyether-based resin obtained by an oxidation polymerization is not admitted as satisfactory in the solubility into a solvent. For example, JP-A Nos. 9-202823 and 9-202824 disclose an application example of a polyether-based resin to a material having lower dielectric constant using a Ullmann""s reaction.
Multilevel interconnect for high speed LSI needs low dielectric constant materials for inter-level layer dielectrics. Moreover, in the production process, the chemical resistance and mechanical strength of the insulation film are extremely important for inter-level dielectrics. Particularly when an insulation film is coated and sintered before patterning thereon by lithography, a process for contact with a developer (alkali aqueous solution, organic solvent) and a process for contact with a resist stripper containing an organic amine in releasing a resist are present, therefore, it is essential that the insulation film can endure these chemicals. Further, due to physical operations such as Chemical Mechanical Polishing (CMP) and the like, the insulation film is required to have certain mechanical strength, and strict adhesion is required to a material to be coated on which the insulation film is formed. However, when a known polyether-based resin for forming an insulation film, for example, a polyether polymer obtained by the above-mentioned Ullmann""s reaction, is used, insufficient chemical resistance or film strength is problematical and improvement thereof is required.
The object of the present invention is to provide a thermosetting polyether resin which can be used as an inter-layer insulation material which has excellent chemical resistance and film strength, or a polyether resin having a low dielectric constant having a low relative dielectric constant which can be applied to a hypervelocity computing device, a method for producing the same, and a coating solution which forms an insulation film having a low electric constant, and excellent in chemical resistance and film strength.
The present inventors have investigated various resins, and resultantly, found that a polyether having a specific structure shows excellent relative dielectric constant as an inter-layer insulation material and chemical resistance and film strength can be manifested by further introduction of a specific functional group, and have completed the present invention.
Namely, the present invention relates to [I] a thermosetting polyether resin obtained by polycondensing a dihalogen compound with a bisphenol compound to obtain a polyether resin having a repeating unit represented by the formula (1), and introducing a functional group which causes a cross-linking reaction by heating into the resulted polyether resin; 
wherein each of R1 to R8 is independently selected from the group consisting of hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, a cycloalkyl group having 4 to 10 carbon atoms which may be substituted, a OR9 group, a phenyl group which may be substituted; R9 is selected from the group consisting of hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, a cycloalkyl group having 4 to 10 carbon atoms which may be substituted, and a phenyl group which may be substituted; X is selected from any one or more groups described below; Y is selected from a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or any one or more of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94 and xe2x80x94SO2xe2x80x94; 
each of Q1 to Q12 is independently selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted, a cycloalkyl group having 4 to 10 carbon atoms which may be substituted and a phenyl group which may be substituted; m represents an integer from 0 to 4; n represents an integer from 0 to 3; Z is selected from the group consisting of hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, a xe2x80x94OZ1 group, and a xe2x80x94N(Z2)(Z3) group; each of Z1 to Z3 independently selected from the group consisting of hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, and a group carrying an ether group having 1 to 10 carbon atoms.
The present invention relates to [II] a polyether resin having a low dielectric constant represented by the formula (3): 
wherein, R1 to R8 and Q1 to Q12 are as defined in the formula (1), however, at least one of R1 to R8 and Q1 to Q12 is selected from an alkyl group having 4 to 10 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms.
Further, the present invention relates to [III] a coating solution for forming an insulation film wherein the solution comprises the above-mentioned thermosetting polyether resin or polyether resin having a low dielectric constant.
Then, the present invention will be illustrated in detail.
The polyether resin in the present invention comprises a repeating unit represented by the formula (1) obtained by condensing a dihalide compound represented by the formula (4) with a bisphenol compound represented by the formula (5), and may have two or more of different repeating units represented by the formula (1). In the formula, each of R1 to R8 is independently selected from the group consisting of hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, a cycloalkyl group having 4 to 10 carbon atoms which may be substituted, a OR9 group, and a phenyl group which may be substituted. R9 is selected from the group consisting of hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be substituted, a cycloalkyl group having 4 to 10 carbon atoms which may be substituted, and a phenyl group which may be substituted,
Axe2x80x94Xxe2x80x94Axe2x80x83xe2x80x83(4)
wherein, X is as defined in the formula (1). A represents any of fluorine atom, chlorine atom, bromine atom, iodine atom, 
wherein, R1 to R8 and Y are as defined in the formula (1).
As the alkyl group having 1 to 10 carbon atoms which may be substituted, branched or linear alkyl groups having 1 to 10 carbon atoms are listed. Examples thereof include hydrocarbon groups such as a methyl group, ethyl group, n-propyl group, iso-propyl group, butyl group, t-butyl group, pentyl group, hexyl group, octyl group, decyl group and the like, and these may appropriately have a substituent. Substituents which can usually introduced into a hydrocarbon group are exemplified as this substituent. Among them, fluorine atom, chlorine atom, hydroxyl group and the like are preferable. Examples of such an alkyl group include a fluoromethyl group, trifluoromethyl group, fluoroethyl group, 1,1,1-trifluoroethyl group, perfluoroethyl group, fluorobutyl group, perfluorobutyl group, fluorohexyl group, perfluorohexyl group, fluorooctyl group, perfluorooctyl group, fluorodecyl group, perfluorodecyl group, chloromethyl group, trichloromethyl group, chloroethyl group, 1,1,1-trichloroethyl group, chlorobutyl group, chlorohexyl group, chlorooctyl group, chlorodecyl group, hydroxymethyl group, hydroxyethyl group, hydroxybutyl group, hydroxyhexyl group, hydroxyoctyl group, hydroxydecyl group and the like, and isomers thereof. The alkyl group having 4 to 10 carbon atoms which may be substituted may also be a group having a single ring structure or a group in which a plurality of rings are bonded by cross-linking. Examples thereof include groups such as a cyclobutyl group, cyclopentyl group, cyclohexyl group, methylcyclohexyl group, dimethylcyclohexyl group, ethylcyclohexyl group, butylcyclohexyl group, cyclooctyl group, methylcyclooctyl group, dimethylcyclooctyl group, ethylcyclooctyl group, bicyclobutyl group, spiropentane group, bicyclo[3.1.0]hexyl group, cubane group, norbornene group and the like, and these may appropriately have a substituent. Substituents which can usually introduced into a hydrocarbon group are exemplified as this substituent. Among them, fluorine atom, chlorine atom, hydroxyl group and the like are preferable. Examples of such a cycloalkyl group include a fluorocyclobutyl group, fluorocyclopentyl group, fluorocyclohexyl group, fluoromethylcyclohexyl group, difluorocyclobutyl group, difluorocyclopentyl group, difluorocyclohexyl group, perfluorocyclobutyl group, perfluorocyclohexyl group, perfluorocyclooctyl group, chlorocyclobutyl group, chlorocyclopentyl group, chlorocyclohexyl group, chloromethylcyclohexyl group, dichlorocyclobutyl group, dichlorocyclopentyl group, dichlorocyclohexyl group, hydroxycyclobutyl group, hydroxycyclopentyl group, hydroxycyclohexyl group, hydroxymethylcyclohexyl group, dihydroxycyclobutyl group, dihydroxycyclopentyl group, dihydroxycyclohexyl group and the like, and isomers thereof. The phenyl group which may be substituted may be an unsubstituted phenyl group or a group to which 1 to 5 substituents from alkyl groups, F atom, Cl atom or hydroxyl group are bonded. Examples thereof include a phenyl group, methylphenyl group, ethylphenyl group, dimethylphenyl group, hexamethylphenyl group, fluorophenyl group, difluorophenyl group, hexafluorophenyl group, fluorotoluyl group, difluorotoluyl group, chlorophenyl group, dichlorophenyl group, hexachlorophenyl group, chlorotoluyl group, dichlorotoluyl group, hydroxyphenyl group, dihydroxyphenyl group, hydroxytoluyl group, dihydroxytoluyl group and the like.
In the formula (1), Y is selected from the group consisting of a single bond, a hydrocarbon group having 1 to 20 carbon atoms, and any one or more of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94 and xe2x80x94SO2xe2x80x94.
Examples of the above-mentioned hydrocarbon group having 1 to 20 carbon atoms include, but are not limited to, xe2x80x94CH2xe2x80x94, xe2x80x94CH(CH3)xe2x80x94, xe2x80x94C(CH3)2xe2x80x94, xe2x80x94C(CH3)2xe2x80x94C6H4xe2x80x94C(CH3)2xe2x80x94 (including various isomers), xe2x80x94CHxe2x95x90CHxe2x80x94, 
and the like.
Each of Q1 and Q12 is independently selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted, a cycloalkyl group having 4 to 10 carbon atoms which may be substituted, and a phenyl group which may be substitited. m represents an integer from 0 to 4, n represents an integer from 0 to 3. Z is selected from the group consisting of hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, a xe2x80x94OZ1 group, and a xe2x80x94N(Z2)(Z3) group. Each of Z1 to Z3 independently selected from the group consisting of hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, and a group carrying an ether group having 1 to 10 carbon atoms. The alkyl group having 1 to 10 carbon atoms which may be substituted may be branched or linear like in the above-mentioned case, and fluorine atom, chlorine atom, hydroxyl group may be substituted thereon. The cycloalkyl group having 4 to 10 carbon atoms which may be substituted may also be a group having a single ring structure or a group in which a plurality of rings are bonded by cross-linking, like in the above-mentioned case. The phenyl group which may be substituted may be an unsubstituted phenyl group or a group to which 1 to 5 substituents from alkyl groups, flourine atom, cholrine atom or hydroxyl group are bonded, like in the above-mentioned case.
The thermosetting polyether resin of the present invention is obtained by introducing a functional group which causes a cross-linking reaction by heating into the above-mentioned polyether. The heating generally means that a resin is subjected to heating at a temperature of not less than room temperature, and the cross-linking means a reaction in which a chemical bond is formed in a molecule and/or between molecules to form a polymer network structure.
As the functional group which causes a cross-linking reaction by heating, to be introduced into the above-described formula (1), there are exemplified functional groups containing an unsaturated hydrocarbon group such as an allyl group, propenyl group, propargyl group, butenyl group and the like, alkoxysilyl groups such as a trimethoxysilyl group, triethoxysilyl group and the like, a cyanate group, epoxy group and the like. Particularly, an unsaturated hydrocarbon group and a silyl group having an unsaturated hydrocarbon group are preferable since electric property after occurrence of a cross-linking reaction does not deteriorate, due to small electronic polarization property after curing.
Among them, an allyl group, propargyl group and functional groups represented by the formula (2) are preferable as the above-mentioned functional group which causes a cross-linking reaction, from the standpoint of suppression of deterioration in electronic property, 
wherein, T1 is selected from the group consisting of an alkenyl group having 2 to 10 carbon atoms and an alkynyl group having 2 to 10 carbon atoms. T2 is selected from the group consisting of an alkyl group having 1 to 10 carbon atoms and an arylene group which may be substituted. n is an integer from 1 to 3. When a plurality of T1 groups are present, they may be the same or different, and also when a plurality of T2 groups are present, they may be the same or different.
A reaction agent used in a reaction for introducing the functional group which causes a cross-linking reaction is obtained by using a halide compound corresponding to the above-mentioned functional group. For example, in the case of introduction of an allyl group, allyl chloride, allyl bromide and allyl iodide are used, in the case of introduction of a propargyl group, propargyl chloride and propargyl bromide are used, and in the case of introduction of a functional group represented by the formula (2), compounds represented by the formula (6) are used, respectively as industrially available raw materials. 
T1, T2 and n are as defined in the formula (2). M is selected from fluorine atom, chlorine atom, bromine atom or iodine atom.
For introducing the functional group which causes a cross-linking reaction by heating into the above-mentioned polyether resin, there is a method in which a polyether resin is metallized, namely, hydrogen atom bonded to an aromatic ring in the polyether is substituted with a metal, then, substitution reaction is effected using a halide compound containing the functional group which causes a cross-linking reaction. The solvent used in the metallizing reaction is not particularly restricted, and ether, tetrahydrofuran and the like are suitable from the standpoints of the solubility, reactivity and the like of the polyether resin.
The reaction agent used in the metallizing reaction is not particularly restricted, and examples thereof include lithium, sodium, n-butyllithium, sec-butyllithium, tert-butyllithium and the like, and phenyllithium, naphthalenesodium and alkylsodium can also be used. Among them, n-butyllithium available in the form of a n-hexane solution is preferable from the standpoint of workability.
As a polyether resin giving an insulation film having a low relative dielectric constant, a polyether resin having a low dielectric constant represented by the formula (3) is exemplified: 
wherein, R1 to R8 and Q1 to Q12 are as defined in the formula (1), however, at least one of R1 to R8 and Q1 to Q12 is selected from the group consisting of an alkyl group having 4 to 10 carbon atoms and a cycloalkyl group having 4 to 10 carbon atoms.
In the formula (3), at least one of R1 to R8 and Q1 to Q12 is an alkyl group having 4 to 10 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms. Examples of the alkyl group having 4 to 10 carbon atoms include a n-butyl group, sec-butyl group, t-butyl group, n-pentyl group, iso-pentyl group, sec-pentyl group, n-hexyl group, iso-hexyl group, sec-hexyl group, octyl group and decyl group. Examples of the cycloalkyl group having 4 to 10 carbon atoms include a cyclobutyl group, cyclopentyl group, cyclohexyl group, methylcyclohexyl group, dimethylcyclohexyl group, ethylcyclohexyl group, butylcyclohexyl group, cyclooctyl group, methylcyclooctyl group, dimethylcyclooctyl group, ethylcyclooctyl group, bicyclobutyl group, spiropentane group, bicyclo[3.1.0]hexyl group, cubane group, norbornene group and the like.
Further, a polyether resin in which at least one of R1 to R8 and Q1 to Q12 is an alkyl group having 4 to 10 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms are preferable since such a resin reveals a lowered relative dielectric constant. Examples of the alkyl group having 4 to 10 carbon atoms include a sec-butyl group, t-butyl group, iso-pentyl group, sec-pentyl group, iso-hexyl group, sec-hexyl group and the like. The cycloalkyl group having 4 to 10 carbons is as described above.
Further, a t-butyl group, cyclopentyl group and cyclohexyl group are preferably used since they can easily be introduced into an aromatic ring by using isobutylene, t-butyl chloride, cyclopentene, chlorocyclopentene, cyclohexene, chlorocyclohexane and the like which are industrially easily available raw materials.
A bisphenol monomer having an alkyl group having 4 to 10 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms as R1 to R8 can be used more preferably since such as monomer is available industrially. Examples of the available monomer include bis(t-butyl)biphenol, biscyclohexylbiphenol, tetra(t-butyl)biphenol, bis(t-butylhydroxyphenyl)isopropylidene, bis( cyclohexylhydroxyphenyl)isopropylidene, bis(t-butylhydroxyphenyl)cycloheptylidene, bis(cyclohexylhydroxyphenyl)cyclopheptylidene, bis(t-butylhydroxyphenyl)cyclohexylidene, bis(cyclohexylhydroxyphenyl)cyclohexylidene, bis(t-butylhydroxyphenyl)fluorene, bis(cyclohexylhydroxyphenyl)fluorene and the like.
Further, by introducing the above-mentioned functional group which causes a cross-linking reaction by heating into a polyether resin having a low dielectric constant represented by the formula (3), a polyether resin having a low dielectric constant and having not only a low dielectric constant but also excellent mechanical strength and chemical resistance can be obtained.
A polyether resin represented by the formula (1) or (3) can be usually produced by condensation in the presence of an alkali substance. The alkali substance used is not particularly restricted, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. These can be used in the form of solid, or aqueous solution or the like.
When the reactivity of the dihalide compound is low, a catalyst can be used in addition to the alkali substance, if necessary. Specifically, copper, copper chloride (I) or complex salts thereof are listed.
The thermosetting polyether resin or polyether resin having a low dielectric constant is treated by processes such as filtration, washing with a solution dissolved in a water-insoluble solvent, and the like, for removal of inorganic substance such as metals, salt substance and the like, and is provided in the form of an insulation film-forming coating solution dissolved in an organic solvent. Examples of the solvent include alcohols such as methanol, ethanol, isopropyl alcohol, 2-methoxyethanol and the like, esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, propylene glycol monomethyl ether acetate and the like, ketones such as 2-pentanone, 2-heptanone, acetylacetone and the like, ethers such as diethyl ether, dibutyl ether and the like, phenol ethers such as anisole, phenetole and the like.
When a polyether or a thermosetting polyether is dissolved in an organic solvent, the concentration is controlled usually from 5 to 40 wt %, more preferably from 10 to 20 wt %. When the concentration is lower than this range, the film thickness in spin coat may become too thin, requiring repeated coating for obtaining given film thickness. When the concentration is higher than this range, the viscosity may increase, leading to complicated liquid feeding in coating and the like.
The coating solution for forming an insulation film of the present invention comprises the above-mentioned thermosetting polyether resin or polyether resin having a low dielectric constant, and additives such as a surfactant, antioxidant and the like can also be used in the range wherein chemical resistance and film strength dot not deteriorate. Further, a catalyst such as a peroxide or azo compound or the like can also be added for reducing the curing temperature of a thermosetting group having an unsaturated group in the thermosetting polyether resin. Also, a silane coupling can be used together to further improve adhesion. Moreover, mechanical strength can also be improved by compounding a cross-linking agent to the polyether resin having a low dielectric constant.
The coating solution for forming an insulation film of the present invention can be applied on a substrate of a semiconductor device by a spin coat method or dipping method, and cured by a method such as heat treatment, irradiation and the like, to form an insulation film having a low dielectric constant.